Main shaft device

Abstract

A main shaft device is attached to a work machine. The main shaft device is provided with a main shaft that supports a tool or a workpiece, and a main shaft motor that causes the main shaft to rotate. The main shaft device is provided with bearings that are rolling bearings which support the main shaft in an inner race, and a housing and a rear housing that secure an outer race of the bearings. The housing and the rear housing are formed of a material having a coefficient of thermal expansion greater than that of the main shaft.

The invention claimed is: 
     
       1. A spindle device attached to a machine tool and rotates a tool or a workpiece, the spindle device comprising:
 a spindle for supporting the tool or the workpiece; 
 a spindle motor for rotating the spindle; 
 a rolling bearing having an inner ring, rolling elements, and an outer ring, the inner ring supporting the spindle; 
 a bearing support part for securing the outer ring of the rolling bearing, 
 a first coolant supply device for supplying a first coolant to the bearing support part; and 
 a controller for controlling the first coolant supply device so as to adjust temperature of the first coolant supplied by the first coolant supply device; wherein 
 the bearing support part is formed of a material having a thermal expansion coefficient larger than that of the spindle and has a first flow path through which the first coolant flows, 
 the first flow path is disposed on the side of the outer ring of the rolling bearing, 
 the first coolant supply device has a function of adjusting the temperature of the first coolant and supplies the first coolant to the first flow path, and 
 the controller performs a control for maintaining the temperature of the first coolant constant when a rotational speed of the spindle motor is equal to or less than a predetermined determination value, and a control for increasing the temperature of the first coolant as the rotational speed of the spindle motor increases when the rotational speed of the spindle motor is greater than the determination value. 
 
     
     
       2. A spindle device attached to a machine tool and rotates a tool or a workpiece, the spindle device comprising:
 a spindle for supporting the tool or the workpiece; 
 a spindle motor for rotating the spindle; 
 a rolling bearing having an inner ring, rolling elements, and an outer ring, the inner ring supporting the spindle; 
 a bearing support part for securing the outer ring of the rolling bearing, 
 a second coolant supply device for supplying a second coolant to the spindle; and 
 the controller for controlling the second coolant supply device so as to adjust temperature of the second coolant supplied by the second coolant supply device; wherein 
 the bearing support part is formed of a material having a thermal expansion coefficient larger than that of the spindle, 
 the spindle has a second flow path through which the second coolant flows, 
 the second flow path is disposed on the side of the inner ring of the rolling bearing, 
 the second coolant supply device has a function of adjusting the temperature of the second coolant and supplies the second coolant to the second flow path,
 the controller performs a control for maintaining the temperature of the second coolant constant when the rotational speed of the spindle motor is equal to or less than the determination value, and a control for reducing the temperature of the second coolant as the rotational speed of the spindle motor increases when the rotational speed of the spindle motor is greater than the determination value.